Chester Elementary: math

The shaded band is this school's normal range. If nothing about how it works changes, nearly every future year should land inside it. Zero means the typical student just meets the state standard. The small numbers under the years are how many students were tested.

Step 1 · Each year's result

For each grade tested, take the average (mean) scale score from the California Department of Education's results file, and subtract the lowest score that counts as "Standard Met" for that grade. That is the grade's distance from standard. Weight each grade by its share of the students tested, then add the grades up. Grades where the state hides the average because ten or fewer students tested are left out entirely.

2015 from sb_ca2015_1_csv_v3.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	55,009	2442.0	− 2436	6	× 28 / 123	1.4
4	55,010	2459.2	− 2485	−25.8	× 32 / 123	−6.7
5	55,013	2472.5	− 2528	−55.5	× 27 / 123	−12.2
6	55,014	2494.9	− 2552	−57.1	× 36 / 123	−16.7
Sum, rounded to a whole point						−34

2016 from sb_ca2016_1_csv_v3.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	51,102	2428.7	− 2436	−7.3	× 24 / 100	−1.8
4	51,103	2483.9	− 2485	−1.1	× 23 / 100	−0.3
5	51,105	2518.6	− 2528	−9.4	× 26 / 100	−2.4
6	51,107	2507.6	− 2552	−44.4	× 27 / 100	−12
Sum, rounded to a whole point						−16

2017 from sb_ca2017_1_csv_v2.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	52,558	2401.2	− 2436	−34.8	× 35 / 108	−11.3
4	52,559	2452.1	− 2485	−32.9	× 24 / 108	−7.3
5	52,562	2528.7	− 2528	0.7	× 20 / 108	0.1
6	52,563	2514.7	− 2552	−37.3	× 29 / 108	−10
Sum, rounded to a whole point						−28

2018 from sb_ca2018_1_csv_v3.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	52,630	2435.7	− 2436	−0.3	× 30 / 118	−0.1
4	52,631	2467.4	− 2485	−17.6	× 36 / 118	−5.4
5	52,634	2482.1	− 2528	−45.9	× 28 / 118	−10.9
6	52,635	2517.9	− 2552	−34.1	× 24 / 118	−6.9
Sum, rounded to a whole point						−23

2019 from sb_ca2019_1_csv_v4.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	52,811	2441.8	− 2436	5.8	× 27 / 110	1.4
4	52,812	2493.9	− 2485	8.9	× 31 / 110	2.5
5	52,813	2512.1	− 2528	−15.9	× 25 / 110	−3.6
6	52,814	2506.3	− 2552	−45.7	× 27 / 110	−11.2
Sum, rounded to a whole point						−11

2022 from sb_ca2022_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	52,793	2364.1	− 2436	−71.9	× 22 / 104	−15.2
4	52,794	2450.9	− 2485	−34.1	× 32 / 104	−10.5
5	52,795	2483.3	− 2528	−44.7	× 21 / 104	−9
6	52,796	2456.1	− 2552	−95.9	× 29 / 104	−26.7
Sum, rounded to a whole point						−61

2023 from sb_ca2023_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	52,752	2418.3	− 2436	−17.7	× 13 / 80	−2.9
4	52,753	2425.4	− 2485	−59.6	× 26 / 80	−19.4
5	52,754	2445.6	− 2528	−82.4	× 26 / 80	−26.8
6	52,755	2515.3	− 2552	−36.7	× 15 / 80	−6.9
Sum, rounded to a whole point						−56

2024 from sb_ca2024_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	52,582	2398.2	− 2436	−37.8	× 17 / 78	−8.2
4	52,583	2485.3	− 2485	0.3	× 15 / 78	0.1
5	52,584	2480.0	− 2528	−48	× 24 / 78	−14.8
6	52,585	2493.5	− 2552	−58.5	× 22 / 78	−16.5
Sum, rounded to a whole point						−39

2025 from sb_ca2025_1_csv_v1.zip

Grade	Line in file	Average score	Standard Met	Distance	Students	Weighted
3	52,338	2432.8	− 2436	−3.2	× 27 / 86	−1
4	52,339	2465.1	− 2485	−19.9	× 16 / 86	−3.7
5	52,340	2511.1	− 2528	−16.9	× 17 / 86	−3.3
6	52,341	2511.7	− 2552	−40.3	× 26 / 86	−12.2
Sum, rounded to a whole point						−20

Step 2 · The average and the normal range

Average: add the yearly results and divide by how many there are. −34, −16, −28, −23, −11, −61, −56, −39, −20 → −32
Typical year-to-year change: how far the result moved from each year to the next, ignoring up or down. 2015→2016: 18 · 2016→2017: 12 · 2017→2018: 5 · 2018→2019: 12 · 2019→2022: 50 · 2022→2023: 5 · 2023→2024: 17 · 2024→2025: 19 → average 17.3
Normal range: multiply the typical change by 2.66, then add it to the average and subtract it. 17.3 × 2.66 = 46. Upper limit 14, lower limit −78.

Why 2.66? It is the standard factor from quality control, the work of Walter Shewhart and W. Edwards Deming. It turns "how much the result typically changes in a year" into "how far it can wander by chance alone".

Years with no result (no state tests were given in spring 2020) are skipped: the year-to-year change runs from the last year with a result to the next one.

Step 3 · Free or reduced-price meals

The share of enrolled students eligible for free or reduced-price meals. From 2014–15, 2015–16, 2016–17, 2017–18, 2018–19, 2020–21, 2021–22, 2022–23, 2023–24, 2024–25, 2025–26.